The invention relates to a carbonyl groups-containing material and the preparation thereof, and to a process for compounding preparations from said material and the shaped products thus obtained. Macromolecular carbonyl groups-containing compounds for the removal of nitrogen compounds from aqueous fluids are disclosed in German Patent Application No. 23 05 186. The compounds proposed in it are alkenyl aromatic polymers having 0.01 to 1 functional .alpha.-ketoaldehyde group per aromatic ring. These compounds particularly serve to remove urea from the dialysis or ultrafiltration liquid in artificial kidneys. The use of a glyoxyl groups-containing styrene polymer is stated to result in the removal from an aqueous 1M-urea solution of a maximum amount of 61.5 g of urea per kg of polymer in a period of 15 hours.
However, this urea sorption is attained under non-physiological conditions, both as regards urea concentration (about 30 g/l instead of the concentration of 2 g/l in hemodialysis) and pH (pH=10 instead of the physiologically normal pH=7.4). If this known sorbent is used at a urea concentration of 1 g/l and pH=7, a situation which is a nearer approach to physiological conditions, then in 15 hours per kg of sorbent only 4.7 g of urea are fixed, as is given in Example 12.
Other known compounds for the removal of urea from dialysis liquid or blood plasma are described in British Patent Application 2 020 996. They are compounds with aldehyde groups activated and masked by a proton-containing substituent of the second order. The compounds may be sorbed on, for instance, activated carbon.
An experiment was carried out with 100 ml of dialysis liquid to which 10 mmoles of 2-carboxy benzaldehyde and 10 mmoles of urea (6 g/l) had been added. After 3 hours' stirring at 40.degree. C. a decrease in urea concentration of up to about 53% of the initial concentration was measured. Also this value, however, is obtained under non-physiological conditions (pH=4.3, high urea concentration, soluble urea binder).